Over 7% Efficiency of Sb2(S,Se)3 Solar Cells via V-Shaped Bandgap Engineering

Antimony chalcogenides (including Sb 2 S 3 , Sb 2 Se 3 , and Sb 2 (S,Se) 3 alloy) have emerged as promising solar absorber materials. Notably, the Sb 2 (S,Se) 3 alloy possesses continuously tunable bandgap from 1.1 to 1.7 eV, which covers the ideal bandgap for single-junction photovoltaics governed by the Shockley–Queisser theory. Moreover, the bandgap gradient provides effective ways for photogenerated carriers collection and has the potential for high-efficient Sb 2 (S,Se) 3 alloy solar cells. Herein, a V-shaped distributional bandgap in Sb 2 (S,Se) 3 solar cells is reported through a simple dual-source vapor transport deposition process, enabling the synergetic increase of the open-circuit voltage ( V OC ) and short-circuit current ( J SC ). Through careful optimization, a power conversion efficiency of 7.27% under AM1.5G illumination is obtained, with V OC and J SC of 0.46 V and 29.6 mA cm −2 , respectively. This V-shaped bandgap engineering provides an effective method to enhance the device performance and can be extended to other chalcogenide thin-film solar cells such as Sn–X, Ge–X, Cu–Sb–X (X = S and Se), and so on.